The present study will determine whether cancer incidence rates among cosmetologists differ from rats in a control group or differ from the expected values based on the Connecticut population as a whole; excess (if any) will be described in terms of the age and sex of the subjects and the cancer sites involved. The investigators will adapt and standardize the methodology needed for such problems so as to facilitate further studies of occupational cancer based on ascertainment of cases through a cancer registry. The population group under study (all cosmetologists registered in Connecticut who have begun hairdressing school before December, 1965) approximates 12,000 individuals. Two groups will be used as controls: (1) a matched control group consisting of Connecticut school teachers (individually matched by age and sex) and (2) a general populations control group. Cancer cases will be ascertained through linkage of the records of the study and control populations with those of the Connecticut Tumor Registry.